24 hours of light during veg is a debatable topic. And one where there's a lot of opinions. Personally for veg, I've tried 24on, 20on/4off, 18on/6off and just settled on 20on/4off. And I haven't noticed a difference compared to 24on or 18on/6off. Except that I save some on electric and everything has a chance to cool off a bit compared to 24on (bigger deal for hydro growers than soil growers probably).
And this is just further personal opinion but plants have twenty-four hour based circadian rhythms that have a lot to do with hormone production and cycles. Keeping them under 24 hours of light results in a free cycling of their circadian rhythms - which just doesn't happen in nature. They seem to deal with that just fine... but why mess with their biological processes any more than necessary unless there's clear demonstrated gain in doing so?
But moral of the story, I find more benefit in giving them at least a couple of hours of regular "night" per 24 hour cycle than not.
Just MHO.
You might also consider setting up a nursery for seedlings in a small area that uses low wattage. There's no point in running a 600w anything over seedlings.
